Stabilized superregenerator



INVENTORI; lfln frng 1516 .9: BY fair/7r [7 Zdcvrz/dao L. l. ALGASE ET AL STABILIZED SUPERREGENERATOR Filed April 29, 1960 Dec. 4, 1962 nited States fire 3,957,392 STABILIZED SUPERREGENERATOR Lawrence 1. Algase, Bethpage, and Robert C. Lockwood, Huntington, N .Y., assignors to the United States of America as represented by the Secretary of the Navy Filed Apr. 29, 1960, Ser. No. 25,810 4 Claims. (Cl. 331-54) The present invention relates to novel and improved apparatus for stabilizing the performance of a superregenerative repeater oscillator and more particularly to novel and improved apparatus for stabilizing such an oscillator against changes in the characteristics of the load into which it operates.

The performance of a superregenerator is normally critically dependent upon the preselected values of its various circuit impedances. Variation in these impedances often greatly affect the signal output power and gain of the repeater. When such variations occur, the repeater often tends to quench itself at an uncontrollable rate or to oscillate continuously where decay of the signal during the quench interval is insufficeint to prevent signal build-up without external excitation.

It is therefore a principal object of the present invention to provide a novel and improved superregenerative repeater oscillator circuit which is stabilized in operation despite variations in the output load circuit.

It is a further object of the present invention to provide a novel and improved superregenerative oscillator circuit which operates with a constant quench period of minimum duration, a constant maximum amplitude of the output voltage pulse, and a substantially constant pulse shape despite variations in conductance of the output load circuit.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawing wherein the single FIGURE of the drawing is a diagrammatic view of a preferred embodiment of the present invention.

A preferred embodiment of the invention is illustrated in the single FIGURE of the drawing. As shown therein, the control grid bias of the blocking oscillator 3 is controllable by manual adjustment of the potentiometer or the like 5. The output circuit of the blocking oscillator 3 is preferably provided as shown with the shunt resistor 7 and is coupled to the grid circuit of the cathode follower triode V in any suitable manner. The plate circuit of triode V extends from the positive voltage supply line 9 through the tube and resistor 11 and through the parallel arrangement of resistor 13 and condenser 15 to the negative voltage supply line 17. The cathode of triode V is connected to the plate of triode V and to the grid of triode V through the parallel arrangement of resistor 20 and condenser 21. The plate circuit of triode V extends from the positive voltage supply line 9 through resistor 19 and through the tube to the negative supply line 17. The grid of triode V is connected to the plate of triode V through resistor 23 and to the grid of triode V through resistors 25 and 27. The plate circuit of triode V extends from the positive voltage supply line 9 through resistor 29 and through the tube to the negative voltage supply line 17. The grid of triode V is connected to the cathode of triode V and to the grid of triode V through resistors 31 and 27. The plate circuit of triode V extends from ground through the tube, and through resistor 31 to the negative voltage supply line 17. The grid of triode V is connected to the grid of triode V through resistor 33. The cathode of triode V is coupled to the grid of triode V through the R.F. choke 35. The plate circuit of triode V extends from the positive voltage supply line 9 through the choke 37 and through the tube to ground. The tank circuit of triode V which includes the parallel connected inductance coil 39 and adjustable condenser 41 and is driven by the receiving antenna 43 is coupled to the grid of triode V through condenser 45 and to the plate of triode V through condenser 47. The output circuit and transmitting antenna 49 is coupled to the plate circuit in any suitable manner.

In operation, when the Colpitts oscillator circuit of triode V is in its so-called deenergized or decay mode, triode V of the multivibrator circuit conducts heavily and triode V remains cut off. So long as no positive trigger pulse is applied to the grid of triode V triode V continues to conduct, the plate of V is highly negative, and the grid of oscillator triode V remains below its cutoff potential. When the positive pulses of constant periodicity from the blocking oscillator 3 are applied to the grid of cathode follower V triode V conducts and its cathode is driven up to approximately ground potential. The negative cutoff potential for triode V developed and stored across condenser 51 in a manner that will be described more fully hereinafter is quickly discharged and oscillator V begins to oscillate and enters its so-called build-up mode.

The posiive output pulse from blocking oscillator 3 is also "applied through conductor 53 and resistor 33 to the grid of cathode follower V This causes triode V to conduct and the positive pulse which is developed at its cathode is applied to the grid of triode V of the multivibrator. Triode V then fires, and the heavy plate current flow through resistor 29 produces a sharp decrease in potential at its plate and at the grid of triode V This cuts off triode V The potential at the plate of triode V increases sharply and the grid of oscillator V is maintained in its build-up mode even thoughthe positive pulse from blocking oscillator 3 may occur for but a brief interval.

As the amplitude of the oscillations of the circuit of triode V build up, current soon begins to flow in the grid circuit of V and a negative charge accumulates across condenser 51. When this negative charge exceeds the threshold potential for the multivibrator, the negative going pulse fed through resistor 20 and condenser 21 to the grid of triode V cuts triode V off. The potential at the plate of V increases abruptly as does the grid potential of triode V and triode V once again conducts heavily. The negative potential at the plate of triode V maintains triodes V and- V cutoff and the decay mode of the circuit persists until the next positive pulse from the blocking oscillator 3 occurs and the entire cycle is repeated.

It will be noted that by suitably adjusting the control potentiometer 5 in the blocking oscillator circuit, self coherence or oscillation is prevented by making the quench period long enough for oscillations in the grid tank circuit of the Colpitts oscillator to subside or decay a sufficient amount after each build-up interval. As long as the absence of self coherence is assured, the quench period is then adjusted to provide a minimum interval to provide a maximum value of power output consistent with the current and dissipation rating of tube V The peak amplitude of the output pulse of oscillator V is maintained constant by the self-developed grid bias on triode V and the preset critical threshold triggering voltage for triode V of the multivibrator circuit. When the multivibrator switches, the grid of triode V is driven negative very rapidly at the beginning of the decay interval in order to bring the total conductance of the oscillator circuit rapidly to its max'mum positive value and thereby provide rapid decay. In this way, narrow output pulses with wide frequency response are obtained.

It will also be noted that the above described stabilizing circuit automatically compensates for the adverse tendency of the superregenerator to become self-coherent when unavoidable variations in the load conductance occur. During the build-up phase, oscillations increase at a rate proportional to:

l si.l....'+..l.GLmI 26 where Gi, is the conductance of the olad; g is the conductance of the gridtank circuit of the oscillator V and C is the net capacitance of the tank circuit and the load.

since g is the larger of the two conducjtances the smaller the load conductance the more rapidly will oscillations build up tothe predetermined amplitude and the shorter will the build-up interval be. Since the quench period is determined by blocking oscillator 3 and is constant, and the sum of the build-up and decay intervals is constant, the decay interval will be correspondingly longer. This provides theadd'ed time-required for decay when G is-srnall.

-It 'i's therefore seen that by mans of the above described stabilized regenerative circuit, substantially constant signal "output power is obtainedtherefrom by providing a constant quench period of minimum duration, at constant maximum amplitude of the output voltage pulse and a variation in-sh'ape of the output voltag'e pulse to compensate for variations in load conductance.

Obviously many modifications and variations w the present invention are possible in the light of the above teachings. It is therefore to be understood that within "the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. Afstabiliz'ed superregenerative repeater com rising a'blocking oscillator;- a cathode follower circuit coupled to the output of the blocking oscillator; a bistable multivibrator including a pair of triodes; an oscillator having 'a grid leaf self-biasing circuit; and means coupling the grid leak self-biasing circuit of said oscillator to the "output circuit of the cathode follower circuit and to the input circuit of one of said triodes of the multivibrator circuit.

2. A stabilized superregenerative repeater comprising a blocking oscilator; means 'coupled to the blocking oscillator for controlling the frequency thereof; a cathode follower circuit coupled to the output of the blocking oscillator; a bistable multivibrator including a pair of triodes; a Colpitts oscillator having a grid leak selfbiasing circuit; and means coupling the grid leak selfbia'sing circuit of said Colpitts oscillator to the output circuit of the cathode fo lower circuit and to the input circuit of one of said triodes of the multivbrator circuit.

3. A stabilized superregenerative repeater comprising a blocking oscillator; a pair of cathode follower circuits coupled to the output of the blocking oscillator; a bistable multivibrator including a pair of parallel triode circuits; means coupling the output circuit of one of the cathode follower circuits to the input circuit of one of the triode circuits of the multivibrator; a Colpitts oscillator having a grid leak self-biasing circuit; and means coupling the grid leak self-biasing circuit of the oscillator to the output circultof other cathode follower circuit and to the input circuit of the other triode circuit of the multivibrator.

4. A stabilized superi'egenerative repeater comprising a blocking oscillaor'; means coupled to the blocking oscillator for controlling the frequency thereof; a pair of cathode follower circuits coupled to the output of the blocking oscillator; 21 bistable multivibrator including a pair of parallel triode circuits; means coupling the output circuit of one of the cathode follower circuits to the input circuit of one of the triode circuits of the multilvibrat'or; a Colpitts oscillator having a grid leak selfbiasin'g circuit; and means coupling the grid leak selfbiasing circuit of the oscillator to the output circuit of other cathode follower circuit and to the input circuit of the other triode circuit of the multivibrator.

References Cited in the file of this patent -UNITED STATES PATENTS 2,644,061 Crawford June 16, 1936 

